Device and method for detecting the level of a medium

Abstract

according to information representing at least one temperature value acquired on the at least one second input.

The invention claimed is: 
     
       1. A capacitive level-sensor device, for detecting the level of at least one medium contained in a container, the device comprising at least:
 a detection part that includes an array of capacitive elements, the array of capacitive elements comprising at least one series of electrodes on a substrate, the series or each series comprising a plurality of electrodes that are spaced apart from one another according to an axis of detection of the level, the detection part including at least one insulating layer for electrically insulating the electrodes with respect to the at least one medium; and 
 a control circuit having a plurality of first inputs, to which the electrodes are electrically connected, 
 wherein the control circuit is prearranged for carrying out a sequential sampling of the inputs of the plurality of first inputs and for comparing a value representative of electrical capacitance associated to each electrode with at least one corresponding reference threshold or value, 
 wherein the detection part further comprises a temperature sensor for the series, or for each series, the temperature sensor or each temperature sensor being connected to a respective second input of the control circuit, 
 wherein the control circuit is moreover prearranged for carrying out a compensation of at least one from among:
 the value representative of electrical capacitance associated to each electrode; 
 a value indicative of the medium facing each electrode; and 
 the at least one reference threshold or value, 
 
 as a function of information representative of at least one temperature value acquired at the second input, or at each second input, 
 wherein the temperature sensor, or each temperature sensor, is set in an end region of the series, or of each series, in particular a lower end region thereof, and 
 wherein the control circuit is prearranged for detecting a temperature gradient along the axis of detection from the first end region to a second end region of the series, or of each series, as a function of information representative of a temperature value acquired at the at second input via the respective temperature sensor. 
 
     
     
       2. The device according to  claim 1 , wherein:
 the temperature sensor, or each temperature sensor, is in a position corresponding to a first electrode of the series, or of a first electrode of each series, said first electrode being a reference electrode for detection of the series, or of each series, with reference to the axis of detection; and 
 the control circuit is prearranged for carrying out compensation of a raw value representative of electrical capacitance associated to a given electrode of the series, or of each series, on the basis of a value representative of temperature or electrical capacitance compensated in temperature that is associated to the electrode of the same series that is located immediately below the given electrode with reference to the axis of detection. 
 
     
     
       3. The device according to  claim 1 , wherein:
 the at least one reference threshold or value is a fixed threshold or value; and 
 the control circuit is prearranged for carrying out said compensation via modification of at least one value representative of the medium that can face each electrode or at least one value of electrical capacitance that can be detected by each electrode of the series, or of each series, as a function of the information representative of the temperature value acquired at the second input. 
 
     
     
       4. The device according to  claim 1 , wherein the control circuit is prearranged for carrying out compensation of the at least one reference threshold or value by modifying the threshold or the value itself. 
     
     
       5. The device according to  claim 4 , wherein the control circuit is prearranged for modifying the at least one reference threshold or value as a function of at least one from among: information representative of the temperature value acquired at the second input; and a value indicative of the medium that can face each electrode or representative of an electrical capacitance that can be detected by each electrode. 
     
     
       6. The device according to  claim 1 , wherein:
 the detection part comprises a plurality of temperature sensors; 
 the array of capacitive elements comprises a plurality of said series of electrodes, the electrodes of each said series being equal to each other, the electrodes of one said series being different from the electrodes of another said series for at least one of shape and dimensions of the corresponding electrodes; 
 each of said series of electrodes has associated thereto a single one of said temperature sensors; and 
 each temperature sensor is positioned in the detection part in a position corresponding to a predefined electrode of each series, said predefined electrode being the lowermost electrode of the series with reference to the axis of detection. 
 
     
     
       7. The device according to  claim 1 , wherein the control circuit is prearranged for detecting one or more of the following conditions:
 a medium contained in the container is entirely in the fluid state; 
 a medium contained in the container has entirely passed from a fluid state to a solid or frozen state; 
 a medium contained in the container has a predominant fluid part where there float or are immersed parts of the medium in the solid or frozen state (“iceberg effect”); 
 a medium contained in the container is in a phase of passage from a fluid state to a solid state or vice versa, such as freezing or unfreezing; 
 a medium contained in the container includes at least one first part in the solid or frozen state and a second part in the fluid or liquid state, there being set between the first part and the second part a layer of air or gas (“igloo effect”); and 
 a medium contained in the container comprises at least one part in the solid or frozen state overlaid by a part in the fluid or liquid state. 
 
     
     
       8. The device according to  claim 1 , wherein the control circuit comprises one or more from among:
 an arrangement for measuring electrical capacitance, preferably comprising a sampling circuit operatively connected or connectable to each input of the plurality of first inputs; 
 a comparator arrangement, in particular configured for comparing a value determined at one said input with at least one corresponding reference threshold or value; 
 a memory arrangement; and 
 a multiplexer arrangement. 
 
     
     
       9. A method for detecting the level of at least one medium contained in a container, the method comprising:
 providing a detection part that includes an array of capacitive elements, the array of capacitive elements comprising at least one series of electrodes on a substrate, the electrodes being spaced apart from one another according to an axis of detection of the level; 
 providing at least one temperature sensor in the detection part; 
 providing a control circuit having a plurality of first inputs, to which the electrodes are electrically connected, and at least one second input, to which the at least one temperature sensor is electrically connected; 
 carrying out a sequential sampling of the inputs of the plurality of first inputs; and 
 comparing a value representative of the electrical capacitance associated to each electrode with at least one corresponding reference threshold or value, 
 the method comprising the step of carrying out a compensation of at least one from among:
 the value representative of electrical capacitance associated to each electrode; 
 a value indicating the medium facing each electrode; and 
 the at least one reference threshold or value, 
 
 as a function of information representative of a value of temperature acquired via the at least one temperature sensor, 
 wherein said compensation comprises the steps of: 
 i) measuring one said representative value not compensated in temperature P 1  for the first electrode of the series; 
 ii) measuring effective temperature in a position corresponding to the first electrode, via the at least one temperature sensor positioned in the same area as the first electrode; 
 iii) applying a compensation mathematics to said representative value not compensated in temperature P 1  of step i), using the measurement supplied by the at least one temperature sensor of step ii), thereby obtaining a representative value compensated in temperature P 1  Comp for the first electrode; 
 iv) measuring one said representative value not compensated in temperature P 2  for a second electrode of the series; 
 v) calculating the difference D 2  between said representative value not compensated in temperature P 2  of the second electrode and said representative value not compensated in temperature P 1  of the first electrode, by the formula D 2 =P 2 −P 1 ; 
 vi) calculating the difference D 1  between said representative value compensated in temperature P 1  Comp of the first electrode and said representative value not compensated in temperature P 2  of the second electrode, by the formula D 1 =P 1  Comp−P 1 ; 
 vii) calculating a compensated threshold T 1  Comp for the first electrode as algebraic sum of a predefined nominal threshold T 1  thereof and half of the difference D 1  of step vi), by the formula T 1  Comp=T 1 +D 1 /2; 
 viii) calculating a compensated threshold T 2  Comp for the second electrode as algebraic sum of a predefined nominal threshold T 2  thereof and half of the difference of step v), by the formula T 2  Comp=T 2 +D 2 /2; 
 ix) repeating steps vii) and viii) to obtain all the values of the thresholds compensated in temperature T x  Comp of the possible remaining electrodes of the series starting from the corresponding predefined nominal thresholds T x , by the formula T x  Comp=T x +D x /2 with D x =P x −P x-1 , where x ranges between 3 and the number of the electrodes of the series. 
 
     
     
       10. The method according to  claim 9 , comprising:
 positioning the at least one temperature sensor, or each temperature sensor, in a position corresponding to a first electrode of the series, or in a position corresponding to a first electrode of each series, said first electrode being a reference electrode for the detection of the series, or of each series, with reference to the axis of detection; and 
 carrying out compensation of a raw value representative of electrical capacitance associated to a given electrode of the series, or of each series, on the basis of a value representative of temperature or of electrical capacitance compensated in temperature that is associated to the electrode of the same series that is located immediately underneath the given electrode, with reference to the axis of detection. 
 
     
     
       11. The method according to  claim 9 , comprising:
 predefining the at least one reference threshold or value as fixed threshold or value; and 
 carrying out said compensation via modification of at least one value representative of the medium that can face each electrode of the series or at least one value of electrical capacitance that can be detected by each electrode of the series, or of each series, as a function of information representative of the value of temperature acquired via the at least one temperature sensor. 
 
     
     
       12. The method according to  claim 9 , comprising:
 carrying out compensation of the at least one reference threshold or value by modifying the threshold or value itself, in particular as a function of at least one of:
 information representative of the value of temperature acquired via the at least one temperature sensor; and 
 a value indicative of the medium that can face each electrode or representative of an electrical capacitance that can be detected by each electrode. 
 
 
     
     
       13. The method according to  claim 9 , comprising:
 providing the detection part with a plurality of temperature sensors; 
 providing the array of capacitive elements with a plurality of series of electrodes, the electrodes of each series being equal to each other, the electrodes of one series being different from the electrodes of another series for at least one of the shape and the dimensions of the corresponding electrodes; 
 associating to each of said series of electrodes a single one of said temperature sensors; and 
 positioning each temperature sensor on the detection part in a position corresponding to a predefined electrode of each series, said predefined electrode being preferably the lowermost electrode of the series with reference to the axis of detection. 
 
     
     
       14. The method according to  claim 9 , comprising:
 arranging the at least one temperature sensor in an end region of the detection part, in particular a lower end region thereof; and 
 detecting a temperature gradient along the axis of detection from the first end region to a second end region of the detection part, as a function of information representative of at least one value of temperature acquired via the at least one temperature sensor. 
 
     
     
       15. A capacitive level-sensor device, for detecting the level of at least one medium contained in a container, the device comprising at least:
 a detection part that includes an array of capacitive elements, the array of capacitive elements comprising at least one series of electrodes on a substrate, the electrodes being set at a distance from one another according to an axis of detection of the level; and 
 a control circuit having a plurality of first inputs, to which the electrodes are electrically connected, 
 wherein the detection part further comprises at least one temperature sensor, connected to at least one respective second input of the control circuit, 
 wherein the control circuit is prearranged for deducing the medium facing each electrode and/or the level thereof and/or for detecting a temperature gradient along the axis of detection on the basis of information acquired via the electrodes and of information acquired via the at least one temperature sensor, 
 wherein the control circuit comprises a controller and a memory integrated or associated thereto, the memory comprising instructions implementing the method of  claim 9 . 
 
     
     
       16. A method for detecting the level of at least one medium contained in a container, the method comprising:
 providing a detection part that includes an array of capacitive elements, the array of capacitive elements comprising at least one series of electrodes on a substrate, the electrodes being spaced apart from one another according to an axis of detection of the level; 
 providing at least one temperature sensor in the detection part; 
 providing a control circuit having a plurality of first inputs, to which the electrodes are electrically connected, and at least one second input, to which the at least one temperature sensor is electrically connected; 
 carrying out a sequential sampling of the inputs of the plurality of first inputs; and 
 comparing a value representative of the electrical capacitance associated to each electrode with at least one corresponding reference threshold or value, 
 the method comprising the step of carrying out a compensation of at least one from among:
 the value representative of electrical capacitance associated to each electrode; 
 a value indicating the medium facing each electrode; and 
 the at least one reference threshold or value, 
 
 as a function of information representative of a value of temperature acquired via the at least one temperature sensor, 
 wherein said compensation comprises the steps of: 
 i) measuring one said representative value not compensated in temperature P 1  for a first electrode of the series; 
 ii) measuring effective temperature in a position corresponding to the first electrode, via the at least one temperature sensor positioned in the same area as the first electrode; 
 iii) applying a compensation mathematics to said representative value not compensated in temperature of step i), using the measurement supplied by the at least one temperature sensor of step ii), thereby obtaining a representative value compensated in temperature P 1  Comp for the first electrode; 
 iv) measuring one said representative value not compensated in temperature P 2  for a second electrode of the series; 
 v) calculating the difference D 2  between said representative value not compensated in temperature P 2  of the second electrode and said representative value not compensated in temperature P 1  of the first electrode, by the formula D 2 =P 2 −P 1 ; 
 vi) adding to the difference D 2  of step v) said representative value compensated in temperature P 1  Comp of step iii), thereby obtaining a representative value compensated in temperature P 2  Comp for the second electrode, by the formula P 2  Comp=D 2 +P 1  Comp; 
 vii) repeating steps v) and vi) to obtain all the representative values compensated in temperature P x  Comp of the possible remaining electrodes of the series, by the formula P x  Comp=D x +P x-1  Comp, where x ranges between 3 and the number of the electrodes in the series, or else repeating steps v) and vi) using always in step vi) said representative value compensated in temperature P 1  Comp of the first electrode, to obtain all the representative values compensated in temperature P x  Comp of the possible remaining electrodes of the series, by the formula P x  Comp=D x +P 1  Comp, where x ranges between 3 and the number of the electrodes in the series. 
 
     
     
       17. A capacitive level-sensor device, for detecting the level of at least one medium contained in a container, the device comprising at least:
 a detection part that includes an array of capacitive elements, the array of capacitive elements comprising at least one series of electrodes on a substrate, the electrodes being set at a distance from one another according to an axis of detection of the level; and 
 a control circuit having a plurality of first inputs, to which the electrodes are electrically connected, 
 wherein the detection part further comprises at least one temperature sensor, connected to at least one respective second input of the control circuit, 
 wherein the control circuit is prearranged for deducing the medium facing each electrode and/or the level thereof and/or for detecting a temperature gradient along the axis of detection on the basis of information acquired via the electrodes and of information acquired via the at least one temperature sensor, 
 wherein the control circuit comprises a controller and a memory integrated or associated thereto, the memory comprising instructions implementing the method of  claim 16 . 
 
     
     
       18. A method for detecting the level of at least one medium contained in a container, the method comprising:
 providing a detection part that includes an array of capacitive elements, the array of capacitive elements comprising at least one series of electrodes on a substrate, the electrodes being spaced apart from one another according to an axis of detection of the level; 
 providing at least one temperature sensor in the detection part; 
 providing a control circuit having a plurality of first inputs, to which the electrodes are electrically connected, and at least one second input, to which the at least one temperature sensor is electrically connected; 
 carrying out a sequential sampling of the inputs of the plurality of first inputs; and 
 comparing a value representative of the electrical capacitance associated to each electrode with at least one corresponding reference threshold or value, 
 the method comprising the step of carrying out a compensation of at least one from among:
 the value representative of electrical capacitance associated to each electrode; 
 a value indicating the medium facing each electrode; and 
 the at least one reference threshold or value, 
 
 as a function of information representative of a value of temperature acquired via the at least one temperature sensor, 
 wherein said compensation comprises the steps of: 
 i) measuring one said representative value not compensated in temperature P 1  for the first electrode; 
 ii) measuring effective temperature in a position corresponding to the first electrode, via the at least one temperature sensor positioned in the same area as the first electrode; 
 iii) applying a compensation mathematics to said representative value not compensated in temperature P 1  of step i), using the measurement supplied by the at least one temperature sensor of step ii), thereby obtaining a temperature-compensated representative value P 1  Comp for the first electrode; 
 iv) measuring one said representative value not compensated in temperature P 2  for the second electrode; 
 v) calculating the difference D 2  between said representative value not compensated in temperature P 2  of the second electrode and said representative value not compensated in temperature P 1  of the first electrode, by the formula D 2 =P 2 −P 1 ; 
 vi) adding to the difference D 2  of step v) said representative value compensated in temperature P 1  Comp of step iii), thereby obtaining a temperature-compensated representative value P 2  Comp for the second electrode, by the formula P 2  Comp=D 2 +P 1  Comp; 
 where, in the absence of detection of a transition between two different media in the container, the following step is carried out; 
 vii-a) repeating steps v) and vi) to obtain all the representative values compensated in temperature P x  Comp of the possible remaining electrodes of the series, by the formula P x  Comp=D x +P x-1  Comp, where x ranges between 3 and the number of the electrodes in the series; 
 or else, in the presence of detection of a transition between two different media in the container, the following step is carried out; 
 vii-b) repeating steps v) and vi) using in step v) a value representative of the electrical capacitance compensated in temperature P y  Comp of an electrode at which one said transition has been detected, to obtain all the representative values compensated in temperature P x  Comp of the possible remaining electrodes of the series, by the formula P x  Comp=D x +P y  Comp, where x ranges between 3 and the number of the electrodes in the series and y is smaller than x and identifies said electrode at which the last transition has been detected. 
 
     
     
       19. A capacitive level-sensor device, for detecting the level of at least one medium contained in a container, the device comprising at least:
 a detection part that includes an array of capacitive elements, the array of capacitive elements comprising at least one series of electrodes on a substrate, the electrodes being set at a distance from one another according to an axis of detection of the level; and 
 a control circuit having a plurality of first inputs, to which the electrodes are electrically connected, 
 wherein the detection part further comprises at least one temperature sensor, connected to at least one respective second input of the control circuit, 
 wherein the control circuit is prearranged for deducing the medium facing each electrode and/or the level thereof and/or for detecting a temperature gradient along the axis of detection on the basis of information acquired via the electrodes and of information acquired via the at least one temperature sensor, 
 wherein the control circuit comprises a controller and a memory integrated or associated thereto, the memory comprising instructions implementing the method of  claim 18 . 
 
     
     
       20. A capacitive level-sensor device, for detecting the level of at least one medium contained in a container, the device comprising at least:
 a detection part that includes an array of capacitive elements, the array of capacitive elements comprising at least one series of electrodes on a substrate, the series or each series comprising a plurality of electrodes that are spaced apart from one another according to an axis of detection of the level, the detection part including at least one insulating layer for electrically insulating the electrodes with respect to the at least one medium; and 
 a control circuit having a plurality of first inputs, to which the electrodes are electrically connected, 
 wherein the control circuit is prearranged for carrying out a sequential sampling of the inputs of the plurality of first inputs and for comparing a value representative of electrical capacitance associated to each electrode with at least one corresponding reference threshold or value, 
 wherein the detection part further comprises a temperature sensor at the series, or at each series, the temperature sensor or each temperature sensor being connected to a respective second input of the control circuit, 
 wherein the control circuit is moreover prearranged for carrying out a compensation of at least one from among:
 the value representative of electrical capacitance associated to each electrode; 
 a value indicative of the medium facing each electrode; 
 the at least one reference threshold or value, 
 
 as a function of information representative of at least one temperature value acquired at said respective second input, 
 wherein the temperature sensor, or each temperature sensor, is in a position corresponding to a first electrode of the series, or of a first electrode of each series, said first electrode being a reference electrode for detection of the series, or of each series, with reference to the axis of detection; 
 and wherein the control circuit is prearranged for carrying out compensation of a raw value representative of electrical capacitance associated to a given electrode of the series, or of each series, on the basis of a value representative of temperature or of electrical capacitance compensated in temperature that is associated to the electrode of the same series that is located immediately below the given electrode, with reference to the axis of detection.